The Oak Ridge Boys were longtime friends to President George H.W. Bush, and on Thursday (Dec. 6), they will get the chance to keep a promise they made to their friend and fan. The legendary country harmony group will travel to Houston to send the statesman off with one final rendition of "Amazing Grace" in his honor.

The group members tell the Tennessean that they've been planning their schedule around the possibility of the elder President Bush's memorial for months now, knowing that his health had been in serious decline. They've been packing suits and ties everywhere they go, knowing the call would be coming and their services would be required. The group are scheduled to take a private jet after their concert in Spokane, Wash., on Wednesday night (Dec. 5) and fly overnight to Houston, where they will have just four hours before they have to start preparing for the service.

They don't mind the tight schedule at all if it means they get to honor the 41st president of the United States one last time. “It’s what you do for friends,” singer Duane Allen tells the Tennessean.

Allen's ties to Bush go back the furthest, all the way to the 1960s, when he and some friends got hired to distribute flyers for a campaign Bush was running in Texas. The entire group met Bush when he was serving as vice-president to Ronald Regan in the '80s, when they were booked to perform at a barbecue at the White House. Bush had to depart for a scheduled trip to Africa before they sang, but he was such a big fan that he came charging over to their soundcheck with a bag over his shoulder, eager to hear them before he had to go.

“He said, 'I’m a huge country music fan and you’re my favorite group,'" Allen recalls. "' Is there any way you can do some songs for me?’”

The group readily obliged, singing some deep album cuts that Bush requested, while he gave them all vice-presidential T-shirts from his bag.

That touched off a friendship that would last decades and sometimes found the Oak Ridge Boys flying to the Bush family compound in Kennebunkport, Maine, with their wives to spend parts of the summer with the Bushes and perform for them privately. The group sang "Amazing Grace" at Bush's presidential inauguration, and they performed it for him privately both in the White House and at his family home over the years.

"We last went two years ago and had lunch with them," Allen recalls. "Those were some of the most special times in our lives.”

Bush died Friday night (Nov. 30) at the age of 94. He had written that he wanted the group to perform the classic gospel hymn at his funeral service years ago, and they have been in contact with his family for the last six months as his health declined, with a call coming in the last month to inform them that his condition had worsened. They will sing "Amazing Grace" on Thursday at Bush's funeral service at St. Episcopal Church in Houston, which takes place one day after his formal state funeral at Washington National Cathedral in Washington D.C.

"President Bush means so much to us," Oaks singer Richard Sterban tells the Tennessean. "There's no way we wouldn't do it. He always taught us to do the right thing, and it is a tremendous honor. One final time here on this earth, we're going to sing it for him and we believe in our hearts we'll see him again one day and we'll sing it for him again."